// Heads up: you need to compile this example with `--features icon_loading`.
// `Icon::from_path` won't be available otherwise, though for your own applications, you could use
// `Icon::from_rgba` if you don't want to depend on the `image` crate.
extern crate winit;
#[cfg(feature = "icon_loading")]
extern crate image;
use winit::Icon;
#[cfg(feature = "icon_loading")]
fn main() {
// You'll have to choose an icon size at your own discretion. On X11, the desired size varies
// by WM, and on Windows, you still have to account for screen scaling. Here we use 32px,
// since it seems to work well enough in most cases. Be careful about going too high, or
// you'll be bitten by the low-quality downscaling built into the WM.
let path = concat!(env!("CARGO_MANIFEST_DIR"), "/examples/icon.png");
// While `Icon::from_path` is the most straightforward, you have a few other options. If you
// want to use the `include_bytes` macro, then pass the result to `Icon::from_bytes`. See the
// docs for the full list of options (you'll have to generate the docs with the `icon_loading`
// feature enabled).
let icon = Icon::from_path(path).expect("Failed to open icon");
let mut events_loop = winit::EventsLoop::new();
let window = winit::WindowBuilder::new()
.with_title("An iconic window!")
// At present, this only does anything on Windows and X11, so if you want to save load
// time, you can put icon loading behind a function that returns `None` on other platforms.
.with_window_icon(Some(icon))
.build(&events_loop)
.unwrap();
events_loop.run_forever(|event| {
if let winit::Event::WindowEvent { event, .. } = event {
use winit::WindowEvent::*;
match event {
CloseRequested => return winit::ControlFlow::Break,
DroppedFile(path) => {
use image::GenericImage;
let icon_image = image::open(path).expect("Failed to open window icon");
let (width, height) = icon_image.dimensions();
const DESIRED_SIZE: u32 = 32;
let (new_width, new_height) = if width == height {
(DESIRED_SIZE, DESIRED_SIZE)
} else {
// Note that this will never divide by zero, due to the previous condition.
let aspect_adjustment = DESIRED_SIZE as f64
/ std::cmp::max(width, height) as f64;
(
(width as f64 * aspect_adjustment) as u32,
(height as f64 * aspect_adjustment) as u32,
)
};
// By scaling the icon ourselves, we get higher-quality filtering and save
// some memory.
let icon = image::imageops::resize(
&icon_image,
new_width,
new_height,
image::FilterType::Lanczos3,
);
let (offset_x, offset_y) = (
(DESIRED_SIZE - new_width) / 2,
(DESIRED_SIZE - new_height) / 2,
);
let mut canvas = image::ImageBuffer::new(DESIRED_SIZE, DESIRED_SIZE);
image::imageops::replace(
&mut canvas,
&icon,
offset_x,
offset_y,
);
window.set_window_icon(Some(canvas.into()));
},
_ => (),
}
}
winit::ControlFlow::Continue
});
}
#[cfg(not(feature = "icon_loading"))]
fn main() {
print!(
r#"This example requires the `icon_loading` feature:
cargo run --example window_icon --features icon_loading
"#);
}